In the past we have played with magnets.

by Rachel

We’ve made our own compasses and explored dollar bills with magnets. Recently though we discovered magnetic mud!!

Have you ever heard of ferrofluid? Until a month or two ago I hadn’t – boy was I missing out!

Today, we broke out our test tubes and left over iron oxide powder from when we made our own tinted sunscreen and made ferrofluid.

Our magnetic mud would make a terrific science fair project!


Ferrofluid is a suspension of tiny, tiny particles of metal that are responsive to magnetic fields (like iron or nickle) mixed into an oil solution. It looks like a liquid and acts like a liquid, but as it contains little bits of magetic-responsive metal, it moves with magnets. For our solution we used powdered rust (iron oxide).

NOTE: You will want to be careful with kids in this experiment. Your kids should not eat the iron. As it is in powder form it *might* be able to be absorbed into the bloodstream if ingested and iron overdoses in kids can be very dangerous. Also, the iron oxide powder stains everything. You might want to mix it outdoors and with disposable containers. I mixed the iron and let the kids play with the test tubes when we were finished.

*SO* cool. I think I played with it for a good twenty minuets when my kids were done. It is mesmerizing.


Supplies – contains affiliate links:

  • Vegetable Oil
  • Iron Oxide Powder
  • Disposable spoon and bowl
  • Test Tube
  • Face mask and/or gloves – you don’t want to inhale the powdered metal or stain your hands.

Mix the iron oxide powder into 1/4 cup of oil. We mixed it a tablespoon at a time and stirred until it was completely mixed in, smooth, no clumps, but also a bit thick. Drop the mud into a test tube filled with water. Cork it and then use the magnet to move the iron “mud” around the tube. Use multiple magnets to see if you can get the blog to move in multiple directions at the same time.

Hope your kids have fun learning about metals, suspensions, magnetic qualities – all with our Iron Mud.

​Rachel is the founder of the blog, One Crazy House. She is the co-author of 101 Kids Activities that are the Bestest, Funnest Ever! and The 101 Coolest Simple Science Experiments. She lives in Fort Worth, Texas with her husband and six children.